In this post: US EPA vs EU drinking water turbidimeters, US EPA 180.1 Turbidimeters, ISO 7027 Turbidimeters Turbidity measurement has long been required for drinking water and potable water treatment and supply. Online turbidity instruments are used in water treatment process and distribution systems globally to measure turbidity or quantify the "cloudiness" or insoluble matter present in the drinking water. Many organic and inorganic items such as sand, silt, solids, precipitates, spores and bacteria found in drinking water contribute to the water cloudiness or turbidity. Turbidimeters are the instruments we use to help operators and treatment facilities quickly detect microorganisms and certain bacteria that could be harmful to the population even in low concentrations. This turbidity measurement instrument has to be accurate, sensitive and reliable to ensure that the drinking water is contaminant free. US EPA vs EU Drinking Water Standards The US EPA has long required turbidimeters and turbidity monitoring as found in the National Primary Drinking Water Regulations and has defined the standard US EPA Method 180.1 Determination of Turbidity by Nephelometry. NTU is the measurement unit used for EPA Method 180.1 and is defined as Nephelometric Turbidity Unit. This 180.1 white light turbidity method measures scattered white light at 90 degrees from the incident light beam. Online US EPA 180.1 process turbidimeters use these NTU measurement units. The EU Drinking Water Directive has identified turbidity measurement as one of several fixed monitoring parameters required for all water that is intended for human consumption. The European drinking water protocol used for turbidimeters is ISO 7027. This method uses the unit FNU which stands for Formazin Nephelometric Unit. In contrast to the US EPA method 180.1, the ISO 7027 method measures in FNU with an infrared light source. The infrared light source and FNU unit is widely used for turbidity instruments globally and often found as the unit for submersible turbidimeters. Online ISO 7027 process turbidimeters also are found with these FNU units as the primary units. Turbidimeters for US EPA Method / US EPA 180.1 The MicroTOL Turbidimeters from HF Scientific offers US EPA 180.1 method white light turbidity…